1. Field of the Invention
The present invention relates to a purified propolis-extract, and its preparation and uses.
2. Description of the prior art
As described in Propolis in natural therapeutics (1983), published by Maloine Editeur S. A., Paris, France, and Fragrance Journal, No. 83, pp. 20-28 and pp. 36-43 (1987), propolis is a resin-like product stored by bees in a beehive, said propolis containing resins, beeswaxes, essential oils, pollens and flavonoids, and having been used in a variety of folk medicines for a long time.
It has been known that the main activities of propolis are antiseptic activity, antioxidation activity, anti-inflammatory activity, local anesthesia activity, virus growth-inhibitory activity and immunoregulatory activity, and that the main components of propolis are flavonoids, aromatic carboxylic acids and aromatic aldehydes.
Propolis, a blackish-brown massive product, can not be readily used intact, and the main components thereof are water-insoluble- or hydrophobic-substances. Thus, propolis is generally used as a propolis extract in the form of liquid (propolis tincture) which is prepared by extracting a crude propolis specimen with a relatively-high concentration solution of a readily water-soluble organic solvent such as ethanol.
Such a propolis extract, however, has the following drawbacks when used in food products such as health foods, agents of anti-susceptive diseases such as prophylactic and therapeutic agents for susceptive-diseases, and cosmetics such as skin-refining agents and skin-whitening agents, and these render the applicability of propolis to a variety of fields difficult.
(1) The components of the propolis extract such as resins and waxes are readily crystallized. When the propolis extract is diluted with saliva, the components are readily crystallized, and this strongly inhibits the absorption and utilization of the effective components of propolis in vivo. When the propolis extract is diluted with water, the components are crystallized, and this renders the handleability very difficult. PA1 (2) The color of the propolis extract, i.e. dark brown, is not satisfactory, and the propolis extract readily becomes opaque. PA1 (3) The flavor and taste of the propolis extract are not satisfactory. The extract has a muddy smell and a stimulant or sharp taste.
Japanese Patent Laid-Open No. 197,523/86 proposes a method to dewax such a propolis extract with ether as an attempt to improve the above-mentioned drawbacks. The method comprises extracting a crude propolis specimen with a readily water-soluble organic solvent such as ethanol, concentrating the resultant extract, and adding to the resultant concentrate with ether to separate or remove waxes.
The method, however, has the following drawbacks: It inevitably requires a step to evaporate a readily water-soluble organic solvent, and this results in an excessive amount of energy consumption and in a complicated process, as well as accompanying a danger of fire because of the use of ether having a relatively-low flashing temperature.
As regards the effects of the method, the components of propolis such as resins and waxes are relatively-well removed, while the color, flavor and taste are still unsatisfactory.
Japanese Patent Laid-Open No. 165,595/89 proposes a method to treat propolis with an activated charcoal and/or a cation exchange resin to effect adsorption.
The method comprises extracting a crude propolis specimen with a readily water-soluble organic solvent such as ethanol, directly adding to the resultant extract with an activated charcoal and/or a cation exchange resin, and separating the effective components of propolis by filtration.
The method, however, has the following drawbacks: It requires a relatively-large amount of an activated charcoal and/or a cation exchange resin in order to satisfiably improve the color, flavor and taste of propolis, and it is not clear how to regenerate such an activated charcoal and cation exchange resin.
As regards the effects of the method, it can improve the color, flavor and taste of propolis, while the effective components of propolis are unfortunately removed by the adsorption on an activated charcoal and/or a cation exchange resin. The removal level of resins and waxes are still insufficient.
Although the combination use of the above-mentioned two methods can be considered, it only results in a much more complicated process and an increment of the production cost. Thus, the combination use is not feasible in an industrial-scale production.
It has been a great demand to establish a high-quality and purified propolis-extract containing the effective components of propolis in a readily absorbable- and utilizable-form in vivo, as well as to its industrially feasible preparation without difficulty.